Low expanding alloy



Patented Oct. 4, 1932 UNITED STATES PATENT OFFICE PETER HIDNERT, OF NEW YORK, N. Y. ASSIGNOR TO THE GOVERNMENT OF TH UNITED STATES, AS REPRESENTED BY THE SECRETARY OF COMMERCE LOW EXPANDING ALLOY .No Drawing.

Application filed October 18, 1929. Serial in. 400,721.

(GRANTED UNDER THE ACT OF MABOH 3, 1883, AS AMENDED APRIL 30, 1928} 370 O. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to him of any royalty thereon.

This invention relates to a new composition of matter, and more particularly to low expanding alloys:

It is an object of the invention to provide an alloy which has a very low, and even abnormally low, coefficient of expansion. Al-

- loys made in accordance with this invention are applicable for purposes where a low coeflicient of expansion is required, for example, in (a) length measures, such as length standar ds; (b) thermostats or thermostatic devices; (c) th. construction of instruments or machines requiring fixed distances between points to be independent of temperature, such as the bar between microscopes of a comparator; (d) in the construction of clocks and watches, the alloys herein described will produce apparatus having greater accuracy for measuring time. These alloys with a negligible expansion will make possible a compensated clock pendulum withoutmercury or nickel steel and thereby induce greater accuracy. Furthermore, the alloysherein described are useful in balance wheels of chronometers to provide good compensation over a range of temperatures.

In carrying out this invention the ingredients are selected and proportioned so that the resulting alloy contains a predominating amount of chromium, say approximately 95% to 99%; a substantial'amount of iron, say 0.1% to 3%; a substantial amountof silicon,

say 0.1% to 2%; and carbon from a trace to a substantial amount, say 1%. Any alloy of these elements within these approximate limits possesses the characteristic property of low thermal expansion for some particular temperature range. The temperature range over which the alloy has a low coefficient of expansion varies with the percentage of the ingredients of the alloy.

There may be added to the alloy, according to the present invention, small quantities of other elements as accessories, say up to'about 1%, in order to improve one or more of the physical or chemical properties of the alloy without increasing the low coeflicient of expansion. Such additional elements may comprise, for example, manganese, nitrogen and oxygen.

An example of an alloy having a low coeflicient of expansion is the following: chromium 98 75 iron silicon 4% carbon accessories comprising manganese,

nitrogen, oxygen This alloy has been found by experiment to have a coelficient of linear expansion less than 1 X 10. per degree centigrade between 15 and +20 centigrade (between 5 and 86 Fahrenheit).

For the temperature range from 100 to 50 centigrade (from 148 to 58 Fahrenheit), thealloy containing approximately 97% chromium, 1% iron, carbon, 1% silicon and accessories comprising manganese, nitrogen, oxygen was found to give excellent results. i The coeflicient of linear expansion of this alloy is approximately I 1 X 10- per degree centigrade between 100 and 50 centigrade (between 148 and 58 Fahrenheit) Having thus described my invention, what I claim is:

1. A low expanding alloy consisting chiefly of chromium, iron, silicon and carbon and containing approximately 98 chromium, approximately iron, approximately 4% silicon and approximately carbon.

2. An alloy suitable for use as a. low expanding metal, containing chromium from 95 to 99%, iron from 0.1 to 3%, silicon from 0.1 to 2%, and a substantial amount of carbon 1 mately 1 X 10- per degree 0., between 100 and 50 0., said alloy containing chromium approximately 97%, iron approximately 1%,

silicon approximately 1%, and carbon ap- 5 proximately 5. An alloy suitable for use as a low expanding metal wherein the coefficient of linear expansion is not more than approximately 1X10 per degree 0., between 100 and 10 50 0., said alloy containing chromium approximately 97%, iron approximately 1% silicon approximately 1%, and carbonapproximately said alloy containing not more than 4 manganese, nitrogen and 16 oxygen.

' PETER HIDNERT. 

